Power-hammer.



c. B. coATIis.

-POWER HAMMER.

APPLICATION FILED Nov. 9, 1914.

Patented July 25, 1916.

2 SHEETS-SHEET l- Z3 I Z6 C. `B. COATES..

POWER HAMMER.

APPLICATION' FILED Novl 9, I9I4.

Patented July 25, 1916. I

2 SHEETS-SHEET 2.

CHARLES B. coATEs, `or ciiIcAs'o, -1`LLINoIs POWER-HAMMER.

referably, though not necessarily, operated y an electric motor as theprime mover and adapted to hammering purposes such as chipping, drillingor riveting by means of a chisel, drill, rivet set, or the like, to oneend` of which the striking member of the drill imparts its blow. I Y

The object of my invention is to provide a simple, eflicientand reliablemachine of this character, characterized 'more particularly by theemployment of a hollow cylinderdirectly reciprocatedl by the electricorother j typeofmotor and containing the hammering piston, theconstruction and 'arrangement ofthe parts being such as to cause suchpiston to deliver quick, snappy land powerful blows upon the inner end-of the.v

shank of the workingtool inserted into the front .end of the barrelWithin which th hollow cylinder is reciprocated:

Another object of my lnventlon is 'to p'rovide simple and efficientmeans for blowing out the cuttings, etc., in a holebeing drilled,

such means being adaptedto pump or force air from the front end of thebarrel into and through the hollow working tool. I also provide meanswherebythis pumping mechanism iscompelled to draw its supply of airdirect from the atmosphere and prevent itl from drawing it through'thewo'rking tool which is objectionablel owing to the fact that such airwould be charged with the dust and dirt created by the drillingoperation.

Other features of advantage and utility in my power hammer will beapparent from the description hereinafter given.

In the drawings Figure l is a central sectional elevationof my powerhammer; Figs. 2, 3 and l sections of the barrel and contained' partsshowing the hollow 'cylinderl and the piston in its dierent positions;Fig. 5 a longitudinal sectionl of the .working tool shown in theforegoing figures; Fig. 6 a.

sectional v'elevation of a modified form` of construction of barrelshowing a .diHerent means for blowing outthe hole and employing theworking tool-with a boref'e'xtending Specication of Letters Patent.

" Patented-amy 25, 1916.

Application tiled November, 1914. Serial No. 870,986.

the-flill length; Figs. 7 8, 9 and 10n views similarto Fig. 6 butshowing the hollow cyllnder and piston in.their`,diiferent positionsoccupied during a cycle ofl operation; Fig.

11 aL longitudinal section of the working tool shown in Figs. 6to lO'andFig. 12 -a section `.on the line 12v-12 of Fig. 6.

My hammer is a power hammer operated preferably directly lby a primemover located 'in the hammer structure itself and while any suitablemotor may be employed as such prime mover, I prefer an electric mo- 'torbecause it is thev most convenient;y and compact and' also the mostdesirable because electric current `which is available everywhere can besupplied thereto at4 any distancewthrough cables. My .invention willtherefore be described in connection with an electric motorlocated inthe hammer' structure itself as the prime mover withoutdintentionorlimitation thereto.

Referring first to the construction illus-` l.trated in Figs. 1 to 5,the machine comprises essentially' the motor structure and its housingor casing at the' upper .or rearwardv end` of the tool and a barrelYconnected therewith and; containingthe working parts, one of which isoperated. directly bythe motor, the barrel also being adapted to receivethe v'working tool at its lower or forward end.

Referring to the details of the construction showin-the motor which ishere an electric motor of any .desired type is-provided with a casing orhousing 1 in which are contained and supported the usual electric motorelements such as the stator 'orifield structure. 2, the rotor orarmature 3 and the brushes 4, (as in the case of -a direct current 0r asingle phase commutator type.) The armature shaft is journaled' at itsends respectively in the' removable end .head or cap l"11 and theend'head 1b whichv is here shown as-integral with the'casing'l, thearmature shaft at this' end projecting through thislatter end head. Forthe con-v venient handling ofthe tool, a handle 5 is provided in whicha'switch is mounted for the control of the 'current to actuate themotor. As shown a rod 16 with a thumb-piece 7 mounted in the graspingportion o f the handle, with its outer end in convenient reach of thethumb or finger of the operator, with the result that the movement ofthe rod is communicated by -means of a bell .crank 8 to a switch contact9. When the are of course electrically insulated from the" handle-andthe metallic structure of the tool.

Referring to the operating connections between the armature shaft andthe hollow cylinder of the'machine or tool hereinafter v specificallydescribed, a counterbalanced center crank 12 is arranged at one side ofthe motor casing and inclosed by a crank case 13 secured to the motorcasing. One of the bearings 14 of the crank is mounted inthe crank case13 and the other in the end head or plate '1b of the motor casing. Inthe present instance one of the crank disks I 12av is formed asa gear.which meshes witha pinion 3a secured to or formed on the outer. orexposed end of the armature sha-ft. 1n the present instance thisarmature pinion is cutdirectly'on the armature shaft itself.

`The -hammer barrel 16'v which may be of suitable dimensions, is adaptedto be secured in the lower end of the crank case 13. In the presentinstance -this barrel is screwythreaded at its upper end in order to.screw into the crank case which is split at its `end and provided witha clampingbolt 17 engaging two similar lugs 13a (one of which is shownin Fig. 1) for the purpose of providing 'a clamp to prevent the barrelfrom unscrewing.- The/lower end of' the barrel is provided with/.anopening in which by preference isarrangeda bushing y18 to receivethe-shank of the chisel or l drin 19.

The crank 12 is provided with a connecting rod or pitman 20 provided lonone'end with a suitable bearing lto lit the crank pin of the crank andon theother end with a v bearing to it'a pin 21 which passes through theparallel lugs 21a on the upper end of a cylinder 22. This cylinderv ishollow, being closed at its upper end preferably by an integral head andclosed at its lower end preferably'by a removable head 23 screw-threadedonto the lower end. lof the cylinder body. l Thisl cylinder taken as awhole is reduced in diameter as to its intermediate portionin order toform an annular space 24 between the inner walls of the barrel and thesaid intermediate `portion of the hollow cylinder.v

In practice and as shown, the upper end'of the cylinder is turned toform a sliding fit in the bore of the barrel. The cylinder head 23 islikewise turned to form a sliding fit in the bore of the barrel so thatwhen it isincorporated with the cylinder body, the cylinder structurehas a sliding lit within the" memes barrel by reason of the provision ofend ,i

heads thereof as described. The cylinder is provided with two sets ofholes 25 and 26 passing throughits walls and communicating between theinterior of the cylinder and the annular space 24. I prefer that each`set shall consist of ya series .of holes although one hole if yofproper area or carrying capacity would be suflicient. The two sets ofholes are arranged in two parallel planes and at such distance from theends of the cylinder that the'piston 27 located therewithin shall beenabled to trap the air at the ends of the cylinder and -be compressedthereby as required in the operation of the machine. The piston 27'is ahammering piston, the same being provided with a head which fits thebore of the cylinder 22 and with a stem or extension27a which lits acentral bore in the cylinder head 23. lt will be understood that boththe head and the stem have sliding fits in the bores in which theytravel.

Describing a cycle o-foperation and beginning with the parts in theirrelative positions shown in Fig. 1 at which time the cylinder 22 isslightly below the uppermosty position and ison its downward stroke, thespace 28 behind or above the piston 27 and the space 29 below or infront of such piston are in communication through the holes 25 and 26and the annular airspace 24 act-l ing as a by-pass between said airspaces 28 and 2 9 so that the air pressure therein is the same. .Thecylinder 22 is now being forced downwardly, that is forwardly, by meansof the electric motor and the crank and the piston 27 being free in thecylinder lags therebehind in its downward movement owing to its inertia,but when the cylyinder is moved downwardly suiliciently far in relationto the piston 27 so that 'the holesv 25 are cut off by the piston fromfurther com-f munication with the air space 28, the air in such lspaceis compressed between the rearward end of the piston andthe upper headof the cylinder. When this compression isy sulicient to overcome theinertia of the piston, the latter then travels in unison with thecylinder, this condition being illus- .trated in Fig. 2. When the crankreaches its lowermost position', the movement of the cylindermomentarily stops and the compressed air in the space 28 drives thepiston' downwardly and `'causes its stem 27El to delever a sharp andsnappy blow en /the end of the shank of the chisel or drill, as shown inFig. 3. It isto be noted'that the holes 25 and'26 are now all incommunication with the air spaces 24,- 28 and -29v`so that there is noback pressure below the piston head nor any reduction in pressureaboveittok 'retard the blow.

In Fig. 4 the cylinder is shown as starting upwardly with the pistonslightly above hose 34.

vcavity 29 is now being compressed. When the upper endof the stroke ofthe cylinder is reached the piston is restored to the position shown inFig. 1 by the expansion of This conpletes a cycle of operation of themachine.

While inl theforegoing description I have referred to the outer orforward end of the tool it.will be understood that this is the properdescription when the tool is held inthis 'downward position asy shown inthe drawings. However, it is Obvious that the tool is capable of workingin any desired position, even 1n an inverted position, inasmuch as the'action depends'largely on the vinertia of the piston. i

If desired the tool or machine may be provided withl a blowingarrangement for blowing out the dust and cuttings from the hole, thenecessary compressed air for this purpose being produced by the machinein itsyoperation. In Fig. 1 I have shown one form of such blowingarrangement and an# other form is shown in Figs. 6 to 12.

Referring to the form illustrated in Fig.- 1, the .lower end of thebarrel is provided with an inlet port 30 communicating directly with theatmosphere and governed by a check valve 31. This end of the barrel visalso provided with an outlet port 32 which is governed by an outlet ordischarge valve 33. The 'discharge port communicates by means of asuitable flexible pipe or hose with the drill steel 19 which in thisparticular instance has a central boreor passage 19a which extends fromthe cutting end lof the t'ool toward the inner or shank end thereof asillustrated in "Fig 5 but not entirely through the tool. The upper endof this passage which isadapted to communicate with the In the presentinstance I attach the delivery end vof the hose to the drill steel in aremovable manner. .and by the means l illustrated in Fig. 5, althoughother means i Yto which nipple the, hose is attached. The y might beadopted' for thepurpose. As shown a'yielding bushing or collar 35ipreferably made of rubber, fits over the drill steel at a point adjacentthe port 19" and a bushing or nipple 36 is passed through an opening inone side. ofv such rubber collar,

rubber collar is held i'n place by means of a split ring which isclamped onto the collar by means v of theclamping bolt 3.8,passingthrough the In Eigsf lugs V39. Y Y y 6 to l12 I have shown a modifiedhas a lateral passage or port 19"- ment ofthe cylinder 22 the stem 'lagsbehind or strap 37 surrounding the same form of construction asrespects` the blowing arrangement, the construction and mode ofoperation of the hammering elements of the machine being the same as inthe vform above described. In this modied form the 'front end ofthebarrel is provided'on its 1nter1or with an annular screw-threadedflange 40 into which' the intermediate por.- tion of a bushing 41screws. The upper end of this bushing 1s provided` with .a marginalvflange 41a provided with a: series of ports 4'1". This lange'tightlyfits the inner walls of the barrel and forms an annular space orvchamber 42 between such marginal flange 41a and the annular flange 40.This chamber is provided with a series of inlet ports 43 and the seriesof ports 41" is governed by a suitable check valve such as the flat ring44 which is adapted to rise to open the ports 41" on the suction strokeof the cylinder 22 l and to close on the otheror, forward strokethereof. yThe bushing 41 has a central re-A stricted bore 45whi'ch is ofthe same diameter as the stem of the piston so that the latter has asliding fit therein for a-purpose hereinafter explained. In thisinstance the working tool 46 has a central bore or pas` sage 46"Lthatthe space within the bushing 41 communicates with such passageand-is adapted to convey any compressed air therein tothe end of thetool.

Referring "o the Operation ofthe blowing Starting With the positionarrangement, and of the parts as shown in Fig. 6, the cylinder 22 is nowon its downward or forward movement, with the result that the air infront is forced from the barrel and through the working tool tothehple'being d illed or the work being done. .The maxima of thecompressing movement of the cylinder 22 is substantially shown in Fig. 7and although the cylinder `22 moves forwardly slightly more than-thereinshown the stem `of the piston lmoves rapidly forwardly to deliver itsblow and in doing so passes through the port 'or passage 45 in thebushing 41,`thereby closing -thel space in front of the piston from thespace in the forwardyend of the bushing. On the return or upwardmoveiston and its as hereinbe ore explained andv thereby keeps the port45 closed during substantially the entire period of the upward-movementof the cylinder this time the fresh air from the atmosphere is drawninwardly'through'the ports 43 and 41" 'and into the forward end of thebarrel l'n advance ofthe cylinder 22 and inrear ofkkthe bushing 41. Notuntil this supply or charge of fresh air is suckedv 1nto the barrel doesthe stem ofthe piston clear the port 45.. The object and purpose of thisconstruction is to assure the pumping of fresh air and the preventing ofany suckwhich extends the entire. length so i s0 that at ing of airmingled with dust upwardly through the working tool with the obviousdisadvantages.

l claim:

j 1. In a power hammer, the combination of a barrel, a power operatedhollow cyl- `inder slidably fitting therein and having completecircumferential contact with the interior walls of the barrel, saidcylinderv having ports in two different points intermediate its lengthand communicating. with the interior of the cylinder, means a'iordingcommunication between the two ports, said barrel walls beingimperio-rate with respect to the external atmosphere where traversed bythecylinder; and-a piston movable in the ing a stem projecting throughone end of the cylinder and adapted to deliver its blow upona workingtool. I

3. In a power hammer, the combination of a barrel, a power operatedhollow cylinder rcciprocable therein and having its intermediate portionreduced in diameter to form mei eee 'an annular air space between it andthe `inner walls of the barrel, said barrel walls being imperfora'tewhere traversed by the l cylinder, and thecylinder having ports in twodifferent points intermediate its length communicating between itsinterior and said annular space, and a piston movable 1n the cylinder,and having a stem. projecting through one end of the cylinder andadapted to deliver its blow upon a working tool.

4. ln a power hammer, the combination of a barrel, a power operatedhollow cylinder reciprocable therein and having-its intermediate portionreduced in diameter to form an annular air space between it and theinner walls of the barrel, said barrel walls being imperforate wheretraversed by the cylinder, and the cylinder having ports in twodifferent points intermediate its length communicating between itsinterior and said annular space, and a piston movable .in the cylinderand having a stem projecting through one end ofthe cylinder and adaptedto deliver its blow upon a working tool, said ports being arranged at ad-istance from the ends of the `cylinder' to provide air compressionspaees for the piston after closing the ports'land such ports togetherwith the annular space forming a by-pass for the yair on opposite sidesof the piston when the latter is ina position between the two ports.

CHARLES B. COATES.

llllfitnesses: i I

' LAWRENCE E. MCGAN'N, Jr.,

ROBERT T. DoBBERx/IAN.

